EVANSVILLE, Indiana (CNN) -- With the pump reading $4.29 a gallon, many of the gas station's patrons are more than a little grumpy. But, one by one, they are approached by Dominique Morson.

Sen. Barack Obama is looking to turn Indiana from red to blue in November.

"Excuse me, sir: Are you registered to vote, and if so is it at your current address?" she asks.

She is polite and persistent, approaching more than two dozen customers during an hour or so at a gas station in Evansville, Indiana, a blue-collar community in southern Indiana not far from the Kentucky border.

Of those she approaches, most say they are already registered, several say they are not, but not interested. Three, though, stop and answer the questions as Morson fills out the state's registration form and then hands it over for the new applicant to sign.

She is not alone. Another handful of Sen. Barack Obama volunteers work the lot, while a dozen more go door to door in Evansville, part of a major grassroots effort aimed at turning one of the most reliably Republican states in presidential politics from red to blue.

"I think we can. I really do," Morson told us during a quick break from her efforts. "We have enough people dedicated to the campaign and enough people who want to see some change, so I think we will."

The fact that Indiana even makes the list of battleground states is itself stunning.

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George W. Bush won the state with 57 percent in 2000 and 60 percent in 2004. The last time Indiana backed a Democrat for president was Lyndon Johnson 44 years ago.

Obama's chances here could rest on the aggressive voter registration and identification effort.

When Obama campaign volunteers register a voter, they also add them to the Obama database, and maintain contact with the voter.

Voter registration is nonpartisan, so there is no way of knowing for sure how many of the new voters -- and those who have erased any eligibility questions by updating their addresses -- are Democrats.

But Republican Secretary of State Todd Rokita, the state's chief elections officer, said Sen. John McCain's campaign had better take notice.

"They have a fight here in Indiana and it is real," Rokita said.

The numbers are dramatic: In 2004, 2.5 million ballots were cast for president in Indiana. And in that entire cycle, the state received some 565,000 new and updated registrations.

This year, the number is already in excess of 562,000 and given the recent spike in activity by campaigns and other organizations, Rokita tells CNN he expects to hit a record 750,000 by the state's October 6 registration deadline.

"I will say that this is the first time I have ever seen a Democratic presidential campaign this engaged in this state. Usually Indiana is No. 1 for the red states on election night when it comes to president," Rokita told CNN in an interview in his state Capitol office in Indianapolis.

While Obama allies are upbeat, to travel the state is to find proof that to turn Indiana blue will be a difficult challenge.

Its farm communities and small towns lean conservative.

In Washington, for example, President Bush carried 75 percent of the vote four years ago. It is a town of about 11,000 and home of the Williams Bros. health care and pharmaceutical supply company.

Mark Williams takes visible pride in the fourth-generation family enterprise, and says in his view McCain is more in tune with his needs as a small businessman, and with his views of the proper role of government in issues like health care reform.

His take is significant: Though he is a registered Republican, Williams was not a Bush fan and voted Democratic for president in 2000 and 2004.

This year, he says experience matters and McCain is far more ready in his view. He also rejects the frequent Obama attempts to link McCain to Bush.

"When you look a the resumes between McCain and Sen. Obama ... Sen. McCain is a lot more experienced," Williams said in an interview in his office filled with memorabilia of a business that stretches back generations.

Of McCain he says, "He has never stood by the rules of the Republicans. He has always voted the way he believes. He tells people what they need to hear not always the most popular thing."

In Evansville, too, there is plenty of evidence that Obama faces long odds here.

As volunteers went door to door in a blue-collar neighborhood Sunday for nearly an hour, they came across just one voter who promised to support the Democratic nominee.

One said he was a definite McCain voter, and several others said they were undecided, and accepted literature from the volunteers.